1. Technical Field
The present invention relates to a mounting board on which a physical quantity sensor is mounted, a sensor unit using such a mounting board, an electronic apparatus and a moving body using the sensor unit, and so on.
2. Related Art
A physical quantity sensor such as an acceleration sensor or an angular velocity sensor is known widely. The physical quantity sensor is mounted on a mounting board with terminals. A land grid array, for example, can be used as the terminals. The land grid array is formed of a plurality of electrodes arranged in a line along the contour of the physical quantity sensor. The electrodes might be arranged, for example, in a line along a side of a rectangular contour in some cases, or might form a line so as to go round the contour in some cases. In general, a solid film of a conductive material is formed in the periphery of the electrodes. Such a solid film is connected to, for example, the ground. The solid film functions as a so-called shield electrode.
JP-A-2007-195145 discloses the related art.
The physical quantity sensor has a temperature characteristic. An output signal in an unloaded state (when no physical quantity to be detected acts on the sensor), namely a zero-point voltage, varies in accordance with the temperature variation. Such a variation is compensated in accordance with the temperature variation. According to the observation by the inventors, it has been found out that if the solid film of the conductive material is formed in the periphery of the electrodes without a space, a singularity (hereinafter referred to as “bias shift”) occurs in a certain specific temperature range in a hysteresis (see, e.g., FIG. 9) of the temperature characteristic of the physical quantity sensor as indicated in the part surrounded by the circle. If such bias shift occurs, the zero-point voltage is made dramatically different in the certain specific temperature range, and it has been unachievable to easily realize a preferable temperature compensation.